All-suture suture anchor systems and methods

ABSTRACT

A method of anchoring soft tissue to a suitable bone site, using a soft suture anchor, includes steps of disposing the soft suture anchor on a shaft of an inserter, and securing a proximal end of a tensioning suture limb, extending proximally from the soft suture anchor, to structure in a handle of the inserter, so that it is maintained in place at a first level of holding tension (T hold ). The inserter shaft is inserted into a bone hole at a desired procedural site, so that the soft suture anchor is positioned at a location where it is to be anchored. A further step involves actuating a control mechanism in the inserter handle to move the structure proximally to apply a second level of deployment tension (T load ) to the tensioning suture limb.

This application claims the benefit under 35 U.S.C. 119(e) of the filingdate of Provisional U.S. Application Ser. No. 61/948,543, entitledAll-Suture Anchor with Inserter, filed on Mar. 5, 2014, and of thefiling date of Provisional. U.S. Application Ser. No. 62/094,866,entitled All-Suture Anchor with Inserter, filed on Dec. 19, 2014. Bothof these prior applications are herein expressly incorporated herein byreference, in their entirety.

BACKGROUND OF THE INVENTION

There are many soft-tissue to bone repair procedures, such as rotatorcuff, SLAP and Bankart lesion repairs, or reconstruction of labraltissue to the glenoid rim, in which a surgeon needs to secure tissue inclose contact with bone by implanting an anchor, pre-loaded with suture,into a hole drilled in the bone at the desired anchor location.Commonly, the anchor which the sutures are attached to is made of eitherplastic such as PEEK or metal such as Titanium or Stainless Steel. Suchanchors function like a nail or screw to secure them into the bone.Floating sutures, loaded into the rigid anchor body, are then passedthrough soft tissue near the anchor and the soft tissue is compressedagainst the bone surface by tying the suture ends into a knot. When thesoft tissue is directly compressed against a bony surface, the body'shealing response will affix the soft tissue to the bone to complete therepair. In the case of an implant pulling out of the bone there is apiece of hard material from that implant floating inside the jointspace. That piece of material could temporary or permanently be stuckwithin the joint, causing damage to the articulating surfaces.

Many surgeons are beginning to favor using all-suture suture anchorsover traditional suture anchors. One particular advantage of using anall-suture anchor is that it requires a smaller hole to be drilled tothe bone. Preserving bone is preferred by surgeons. There are quite afew all-suture anchor designs on the market today intended to capturethis trend.

The JuggerKnot™, by Biomet, has its anchor configuration made of asection of #5-polyester suture. The loaded suture is inserted throughthe length of the #5 suture section of the anchor. The anchor ispreloaded on an inserter at the middle point. The inserter pushes theanchor into a drilled hole in the bone until a desired position isreached. The inserter is then removed. Both suture limbs are lightlypulled to contract the anchor, expanding it laterally against the wallof the drilled hole. This design relies on the friction between thesuture ball of the anchor and the bone. Depending upon the positioninside the hole to which the anchor is deployed or set, anchor slippagemay occur when higher tension applied on the anchor until the anchor maymove to a harder bone surface such as the cortex.

ConMed Linvatec also has introduced an anchor called the Y-Knot™. Theanchor is very much the same construct as the Biomet JuggerKnot anchorin terms of design, but with different suture material. It useshigh-strength suture for the anchor instead of polyester suture. Thetechnique for using the anchor is also very similar as the companysuggests in its own words: “Drill Pilot Hole, Insert Anchor, and Pull-toset.” Since the anchor designs and techniques are similar, the anchorshares the same weakness of relying on friction. Thus, slippage canoccur, and pull out strength could not be adequate.

Another similar anchor is from Stryker and is called Iconix™. The anchoris designed to have opening sections along the sheet portion, whichclaim to provide a bunching effect using targeted compression zones. Themiddle point of the anchor is also preloaded on an inserter and insertedinto a pre-drilled hole. When deployed by applying tension on thepre-loaded suture limbs, instead of the whole section of the anchorexpanding randomly within the hole, those opening sections on the anchorare intended to swing outward laterally up to 3 mm-4 mm. However, suchclaimed expansion dimensions are theoretical only, because the softsuture is not stiff enough to penetrate the hole to achieve suchdimensions in practice.

All of the foregoing anchors are offered in different sizes (defined bythe size of the hole drilled into the bone) and are pre-loaded withdifferent sizes and numbers of floating sutures. All of these anchors,as noted above, are similar in construction: a floating suture orsutures are passed through a tube of larger suture. There may be one ormore windows cut in the tube to allow the construct to bend at certainlocations, as well as to allow the floating sutures to pass between theinside and outside of the tube. All of the anchors are then loaded ontosimilar inserters meant to push the anchor into a tunnel drilled intothe bone. The anchors are wrapped around the top of the inserter shaftand secured in a fork at the tip. The floating sutures are routed alongthe inserter shaft and are secured in a cleat in the inserter handle.

Advantages of all-suture anchors that have resulted in their increasedpopularity in orthopedic procedures include:

a) the need for a smaller bone tunnel, because all-suture anchors deployand change shape inside the bone tunnel, meaning that the drilled holecan be smaller than for rigid anchors with similar strength. Thisresults in less bone removal and the ability to place anchors closertogether when necessary;b) ease of revision, because if an all-suture anchor does not deploycorrectly, or if the surgeon is not comfortable with the bone qualityafter drilling the bone tunnel, the small hole allows the practitionerto drill a slightly larger hole in the same location and to use atraditional rigid anchor. If the anchor is deployed, it is easy for thesurgeon to drill through or remove the anchor in order to implantanother one; andc) patient safety. In some cases, anchors can back out or be pulled outof the bone by patient activity or re-injury. If the anchor is locatedin a joint space, such as in the glenoid, and it pulls out of the boneafter surgery, the soft material will not damage the bone surfaces (suchas the humeral bead) as can be the case with a rigid anchor.

All of the foregoing anchors are also deployed in similar manners. Oncethe anchor is placed at the bottom of the bone tunnel, the floatingsutures are removed from the inserter handle and the inserter isremoved. To deploy the anchor, the physician is required to pull on thefloating sutures. This tension applied to the floating sutures pulls theanchor upwardly in the bone tunnel, and the friction between the anchorand the bone causes the anchor to change shape and expand to create aninterference fit in the tunnel. In addition, the larger diameter of theanchor prevents it from pulling up through the smaller hole in theharder cortical bone near the surface. The floating sutures are thenpassed through soft tissue and the remaining procedural steps areidentical to those of any other pre-loaded suture anchor.

Currently available all-suture anchors require manual tensioning by thepractitioner in order to deploy the anchor, as noted above. Often, toavoid anchor pullout in soft bone, the practitioner will pull gently onone suture limb, then pull on the other, and back and forth in likemanner until the anchor is deployed. The amount of tension required tofully deploy the anchor depends upon the bone quality, as well aspractitioner skill, training, and experience. At a minimum, this resultsin inconsistent tension applied to deploy the anchor. This, in turn,will lead to inconsistent performance, both in cyclic displacement andultimate pull-out strength. If the practitioner is concerned about thebone quality and only pulls gently to deploy the anchor (to avoidpulling the anchor out), the anchor displacement under cyclic loadingwill be greater and the ultimate pullout force could be reduced. Anotherfailure mode is the anchor not expanding properly and pulling out of thebone tunnel during practitioner tensioning. This can happen if the boneis very hard and the anchor cannot properly expand, or if the bone isvery soft and the practitioner pulls hard enough to overcome the maximumpullout force of the anchor.

SUMMARY OF THE INVENTION

The present invention comprises an all-suture anchor together with aninserter and drill guide to deploy the anchor in bone. The inserter isdesigned to pull a specific and consistent range of tension each time inorder to deploy the anchor in a bone tunnel. The drill guide provides alarge footprint at the surface of the bone around the drill hole toprotect the bone during anchor deployment.

The amount of force applied to deploy the anchor is very important toits post-operative performance. For example, if the anchor is deployedby pulling at a particular level of tension on the sutures (40 N in oneparticular example), it will expand and move to a certain position inthe bone tunnel. The sutures are then passed through soft tissue andtied down to secure the tissue against the bone. During post-operativeactivity and rehabilitation by the patient (prior to tissue healing),forces are exerted on the soft tissue and transferred through the sutureto the anchor. If these forces are below the deployment tension level(40 N in our example), the anchor will remain in the same position.However, if the anchor is exposed to loads higher than the deploymentforce, it is likely to be pulled toward the surface of the bone. Thismovement can cause slack in the suture and allow a gap to form betweenthe tissue and the bone, resulting in a failed repair. If the anchor isdeployed at 100 N during surgery, for example, it will remain stable atloads below this value. If it is pulled with too much force duringdeployment (more than its maximum pull-out force in that bone), it maypull out, especially if the bone is very soft or very hard.

Bench testing, cadaver testing, and the literature review have been usedto determine the appropriate minimum load the anchor should withstandpost-operatively. Several cyclic loading studies by Barber et al.Specify cyclic loading from 0 to 60 N to simulate forces applied to thesuture anchors post-operatively, prior to tissue healing. Mazzocca etal. Deemed a peak cyclic load of 100 N (for a 3-anchor construct sharingthe load) to be appropriate for rotator cuff testing. The presentinvention is designed to deploy the anchor with a minimum, preferably,of approximately 60 N of tension so that the anchor will not move whenexposed to this load post-operatively. This is more tension that aphysician can easily apply by hand, especially with only one floatingsuture loaded in the anchor.

Bench and cadaver testing were performed to determine the upper range ofthe tension with which to deploy the anchor. Applying too much tensioncan cause the anchor to pull out of the bone, especially in very soft orvery hard bone. In very soft bone, excessive tension can cause thedeployed anchor to pull upwardly through the soft bone. In very hardbone, the anchor cannot displace bone to fully expand to a largerdiameter inside the tunnel. If it is deployed with more tension that thecompression fit can withstand, the anchor will slide out of the hole.One particular embodiment of the present invention was tested in a rangeof bone block densities that simulate a range from very soft to veryhard bone, as well as human cadaver bones. An upper limit ofapproximately 150 N was found to be appropriate for proper deploymentacross the range of bone densities.

The inventive inserter utilizes a knob to turn a screw to apply tensionto the floating sutures. This design provides a mechanical advantage andallows the inserter to pull more tension to deploy the anchor than asurgeon can reliably pull by hand to achieve the desired range ofdeployment tension (60-150 N).

Another important component of the present inventive system is the drillguide. Most suture anchors on the market utilize a drill guide to helplocate and maintain the position of the drill on the bone surface aswell as to guide the anchor into the hole at the same angle as thedrilled hole. For the described all-suture anchor of the presentinvention, the drill guide plays an integral role and is designed to aidin the anchor deployment. Since the inserter pulls on the anchor with asignificant amount of tension, the opposing reaction force pulls theinserter against the bone surface. If the anchor were deployed without adrill guide, in soft bone, the deployment forces would pull the anchorupwardly toward the surface of the bone and simultaneously pull theinserter shaft downwardly into the bone, and full tension would not bereached. Most drill guides are made from thin-walled tubing to keep theouter diameter as small as possible. However, this thin, knife-kike edgeat the tip can create a cylindrical cut into the bone around the tunnelif forced into the bone. This can also happen if the practitionermallets too hard on the inserter handle. If the inserter handle bottomsout on the drill guide, subsequent malleting will drive the inserter anddrill guide into bone and damage the surface. The drill guide used withthe described anchor and inserter has a much thicker wall section at thetip that provides a larger surface area to resist the downward forces(applied by the inserter during anchor deployment or by the practitionerduring malleting). This downward pressure from the drill guide tip alsoprotects the bone from damage or breaking as the anchor is pulledupwardly during deployment. If the anchor is manually deployed and thepractitioner pulls very hard to deploy the anchor, it will expand andthe force is then transmitted to the bone above it. If the bone is weak,it could break and leave a large crater on the surface of the bone. Inthe inventive system, the drill guide helps to prevent this mode offailure.

Another improvement relates to the construction of the anchor itself.Many anchor designs were built and tested to determine the constructionthat could be inserted into the smallest diameter and shortest holedepth, and at the same time expand consistently to have the lowestcyclic displacement and highest pull-out force.

More particularly, in one aspect of the invention, there is disclosed asoft suture anchoring system which comprises a suture anchor fabricatedentirely of soft material, comprising a length of suture having aplurality of loops disposed therein and further comprising a tensioningsuture limb disposed along the suture anchor and extending from one endof the suture anchor. An inserter is also provided for inserting thesuture anchor into a bone hole, wherein the inserter comprises a shaftfor holding and deploying the suture anchor and a handle proximal to theshaft. The handle comprises a structure attachable to the tensioningsuture limb for holding and maintaining the tensioning limb under afirst level of holding tension (T_(hold)) sufficient to hold thetensioning suture limb in place, and a tensioning mechanism which movesthe structure proximally to apply a second level of deployment tension(T_(load)) to the tensioning limb to expand a lateral dimension of thesuture anchor in order to deploy the anchor.

In one disclosed embodiment of the invention, the structure comprises acrossbar. The crossbar is connected to the shaft, so that the crossbarmoves axially when the shaft moves axially. The tensioning mechanismcomprises a knob connected to a proximal end of the shaft, whereinrotation of the knob causes the shaft to move axially in a proximaldirection. Specifically, in one approach, the proximal end of the shaftcomprises external threads and the knob comprises internal threads whichare engaged with the external threads, wherein rotation of the knobcauses the shaft to be rotatably retracted proximally into the knobbecause of the threaded engagement of the knob and the shaft.

A pinching mechanism is provided for pinching the tensioning suture limbagainst the crossbar. In one embodiment of the invention, the pinchingmechanism comprises a pinching pin disposed adjacent to the crossbar.The pinching pin may be positionally fixed, or it may be axially movableto adjust T_(hold) and T_(load) to a desired level. In illustratedembodiments of the invention, T_(load) is 60 N-150 N. However, incertain cases, using the axially movable pinching pin, the desired levelof T_(hold) and T_(load) is lower than 60 N.

In the disclosed invention embodiments, the shaft comprises an innershaft, and the inserter further comprises an outer shaft surrounding theinner shaft.

In another aspect of the invention, there is disclosed an insertersystem for a soft suture anchoring system, wherein the inserter includesa shaft for holding and deploying a soft suture anchor and a handleproximal to the shaft. The handle comprises a structure attachable tothe tensioning suture limb for holding and maintaining the tensioninglimb under a first level of holding tension (T_(hold)) sufficient tohold the tensioning suture limb in place, and a tensioning mechanismwhich moves the structure proximally to apply a second level ofdeployment tension (T_(load)) to the tensioning limb to expand a lateraldimension of the suture anchor in order to deploy the anchor.

In one disclosed embodiment of the invention, the structure comprises acrossbar. The crossbar is connected to the shaft, so that the crossbarmoves axially when the shaft moves axially. The tensioning mechanismcomprises a knob connected to a proximal end of the shaft, whereinrotation of the knob causes the shaft to move axially in a proximaldirection. Specifically, in one approach, the proximal end of the shaftcomprises external threads and the knob comprises internal threads whichare engaged with the external threads, wherein rotation of the knobcauses the shaft to be rotatably retracted proximally into the knobbecause of the threaded engagement of the knob and the shaft.

A pinching mechanism is provided for pinching the tensioning suture limbagainst the crossbar. In one embodiment of the invention, the pinchingmechanism comprises a pinching pin disposed adjacent to the crossbar.The pinching pin may be positionally fixed, or it may be axially movableto adjust T_(hold) and T_(load) to a desired level. In illustratedembodiments of the invention, T_(load) is 60 N-150 N. However, incertain cases, using the axially movable pinching pin, the desired levelof T_(hold) and T_(load) is lower than 60 N.

In the disclosed invention embodiments, the shaft comprises an innershaft, and the inserter further comprises an outer shaft surrounding theinner shaft.

In yet another aspect of the invention, there is disclosed a method ofanchoring soft tissue to a suitable bone site, using a soft sutureanchor. The method comprises steps of disposing the soft suture anchoron a shaft of an inserter, and securing a proximal end of a tensioningsuture limb extending proximally from the soft suture anchor tostructure in a handle of the inserter, so that it is maintained in placeat a first level of holding tension (T_(hold)). The inserter shaft isinserted into a bone hole at a desired procedural site, so that the softsuture anchor is positioned at a location where it is to be anchored. Afurther step involves actuating a control mechanism in the inserterhandle to move the structure proximally to apply a second level ofdeployment tension (T_(load)) to the tensioning suture limb.

The invention, together with additional features and advantages thereof,may best be understood by reference to the following description takenin conjunction with the accompanying illustrative drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-9 are views illustrating the construction of a suture anchoraccording to a first embodiment of the invention;

FIGS. 10-18 are views illustration the construction of a suture anchoraccording to a second embodiment of the invention;

FIG. 19 is an isometric view of a suture anchor insertion systemincluding an inserter constructed in accordance with the principles ofthe invention;

FIG. 20 is an isometric view of a distal end of the inserter of FIG. 19;

FIG. 21 is a schematic cross-sectional view showing the use of theinserter system of FIGS. 19-20 and/or FIGS. 28-29 to insert a sutureanchor into a bone tunnel;

FIG. 22 is a schematic top view of the handle portion of the inserter ofFIGS. 19-20 and/or FIGS. 28-29, illustrating its inner mechanicalfeatures;

FIG. 23 is a schematic side view of the handle portion shown in FIGS.21-22;

FIGS. 24-27 are views illustrating the construction of a suture anchoraccording to a third embodiment of the invention; and

FIGS. 28 and 29 are schematic views illustrating an alternativeembodiment of the inserter handle of the present invention, which issimilar in all respects to the embodiment illustrated in FIGS. 22-23except for the addition of an ability to adjust tension control of theinserter system.

DETAILED DESCRIPTION OF THE INVENTION

Referring now more particularly to the drawings, there is shown in FIG.1 a suture anchor 10 comprised entirely of a suture material, as well asa floating suture 12. It should be noted, at this juncture, that theinvention comprises an inserter that applies tension to the floatingsutures of an all-suture anchor in order to expand it within the bonetunnel to produce an interference fit of the anchor with the walls ofthe bone tunnel. The construction of the anchor itself also helps toprovide a strong and secure anchor point in the bone. There are twoparticularly preferred methods of constructing the anchor 10 that resultin a large change between the aspect ratio of the non-deployed anchorand the deployed anchor. It is desirable for the anchor 10 to be shortand think for the insertion step of the procedure so that it can fitinto a shallow, small diameter hole. This results in the least volume ofbone removed from the patient. During deployment, the anchor 10 shouldexpand as much as possible to provide compression against the walls ofthe bone tunnel, and to prevent it from pulling through the smalldiameter hole in the cortical bone at the tunnel entrance.

Thus, FIG. 1 illustrates a first embodiment of a suture anchor 10constructed in accordance with the principles of the present invention.This embodiment is a single-loaded anchor. FIG. 2 illustrates anassembly fixture 14, wherein a piece of size 2 suture 16 (anchor suture)is wrapped around pins 18 of the fixture 14, as shown. As shown in FIG.3, a cap 20 is placed on the fixture 14 and a needle 22 with a snareloop 24 on one end is pierced through the anchor suture 16. Then, theassembly 26 is removed from the fixture, as shown in FIG. 4.

Referring to FIG. 5, one free end of the floating suture 12 is passedback and forth through loops 28 formed between the suture 16 and theneedle 22 in the previous step. As shown in FIGS. 6 and 7, one end ofthe anchor suture 16 is placed in the snare loop 24 and pulled backthrough the suture strand.

FIG. 8 illustrates a step wherein the floating suture 12 has been pulledtight, and the ends of the anchor suture have been cut off to completethe anchor construct 10.

Now with reference to FIG. 9, a second embodiment of a suture anchor 10constructed in accordance with the present invention is illustrated.This embodiment is a double-loaded anchor. This embodiment 10 isconstructed as shown in FIGS. 10-18. FIG. 10 illustrates a first step inthe method of constructing the double-loaded anchor 10 of FIG. 9,wherein a needle 22 with a snare loop 24 on the end is passed throughthe core of a size 2 piece of suture 16 (anchor suture). The step isrepeated with a second needle 30 having a snare loop 32 being passedthrough a second piece of suture 16, as shown. In FIG. 11, the long endof second anchor suture 16 is placed into the snare loop 24. The needle22 is pulled to pull the suture end through the core of the secondanchor suture 16. FIG. 12 illustrates the result of this step. Then, thelong end of the first anchor suture 16 is placed in the snare loop 32and pulled through the core of the second anchor suture 16. FIG. 13illustrates the resulting anchor loop 33.

As shown in FIG. 14, to load the floating sutures 12, the loop 33 isplaced over a suture snare 34. The anchor loop 33 is twisted inalternating directions around the suture snare 34, as shown in FIG. 15.Referring to FIG. 16, one free end of a floating suture 12 and two endsof the suture loop 33 are passed through the suture snare 34. The suturesnare 34 is then pulled to pull the floating suture 12 and suture loop33 through the loops in the anchor.

A second floating suture end is then passed through the suture loop 33,as shown in FIG. 17. The loop is pulled in the opposite direction topull the second floating suture through the loops in the anchor.

As represented in FIG. 18, the anchor suture ends are then trimmed tolength, completing the assembly of the second embodiment of the sutureanchor 10.

The two suture anchor embodiments 10 disclosed herein result in anchorsthat can be placed into a shallow, small diameter hole, and then whendeployed by the inserter can be deployed into a large ball which issecurely anchored in the bone tunnel.

Now with reference to FIGS. 19-23, the inserter 36 of the presentinvention will be described. The inserter 36 has two primary functions.A first function is to deliver the anchor 10 into the bone tunnel, and asecond function is to apply tension on the floating sutures 12 to deploythe anchor 10. One embodiment of the inserter 36 is illustrated in FIG.19, comprising several components required to deploy the anchor. Thefollowing describes the anchor 10 loaded with one floating suture.

Inside the inserter 36, which comprises an inner shaft 38 housed withinan outer shaft 39, as well as a handle 44 disposed at a proximal end ofthe outer shaft 39, the floating suture ends are wrapped around acrossbar 46 (FIG. 22). Wrapping the suture around the crossbar 46provides friction in order to tension the floating suture 12 and deploythe anchor 10. After wrapping around the crossbar 46, the suture endspass through a hole in the crossbar 46 and are compressed between apinching pin 48 (FIG. 23) and an inner diameter of a hole in thecrossbar 46. Compressing the sutures between the crossbar hole and thepinching pin 48 provides the small holding tension required to keep thesutures from slipping around the crossbar 46. The crossbar works like acapstan used in sailing. The tension to deploy the anchor (T_(load)) iscounteracted by the sum of: 1) the friction of the suture wrapped aroundthe crossbar, and 2) the friction of the suture compressed by thepinching pin 48 (T_(hold)). The relationship of these opposing forces isdescribed by Eytelwein's formula:T_(load)=T_(hold)e^(ϕμ)where

-   -   ϕ=total angle swept around the Crossbar    -   μ=coefficient of friction between the suture and the crossbar        materials        The design of the illustrated embodiment results in a range of        T_(hold) to achieve the desired deployment tension T_(load)        (60-150 N). The sutures are wrapped two times (Φ=720°=2π        radians) around the crossbar and the coefficient of friction is        determined by the suture and crossbar materials. The size and        length of the pinching pin 48, as well as the hole diameter in        the crossbar 46 were chosen to achieve a specific range of        holding tension, T_(hold). The suture is pinched enough so that        the minimum T_(hold) is high enough to result in a minimum        T_(load) of 60 N and the maximum T_(hold) is low enough to        result in a maximum T_(load) of 150 N. The suture will begin to        slip between the crossbar and the pinching pin when enough force        is applied, keeping T_(load) below the desired value.

Clearly, there are other methods of pinching the suture to provide theholding tension T_(hold), such as spring clips, suture cleats, and thelike. The suture ends are then wrapped inside the handle in such a wayto allow them to unwrap and pay out of the inserter smoothly as it isremoved after deployment.

After the inserter tip and anchor are inserted into the bone tunnel, theanchor is deployed by turning a knob 50 on the proximal end of theinserter 36. The knob 50 has an internal screw thread 51 that engageswith an external thread 51 a on the proximal end of the inner shaft 38.When the knob is rotated, the inner shaft is moved proximally. The innershaft 38 also has a cross pin 52 that prevents it from rotating withinthe inserter 36 and pulls the crossbar 46 along with the inner shaft 38.For the first 9 mm of travel, the inner shaft 38 tip is pulling out ofthe bone tunnel and out from between the two sides of the folded-overanchor. This allows the anchor to move proximally during deployment andprovides space in the bone tunnel for the anchor to deploy. After theinner shaft 38 moves 9 mm, the cross pin 52 contacts the crossbar 46 andbegins to pull it proximally in conjunction with the inner shaft. Thistravel of the crossbar pulls tension on the floating sutures 12 whichenlarges the anchor and causes it to compress inside the bone tunnel.The inner shaft, and crossbar travel for an additional 16 mm, whichresults in 60-150 N of tension (T_(load)) in the floating sutures.

When the inner shaft reaches 20 mm of travel, the pinching pin 48 in thecrossbar 46 contacts a smaller diameter fixed pin 54 in the handle 44(FIG. 23). As it travels from 20 to 25 mm, the pinching pin 48 is pushedout of the crossbar to release the holding tension (T_(hold)) on thesuture ends. When the holding tension drops to zero, the tension on thefloating sutures in the anchor (T_(load)) drops to zero and the suturescan slide and unwrap easily from the crossbar. At this point, theinserter is pulled proximally from the insertion site and the suturesunwrap and pay out of the inserter handle and deployment tube 42.

As noted above, the second anchor configuration 10 is loaded with twofloating sutures 12. In this case, two suture ends are routed up thedeployment tube 42, with two limbs on either side of the inner shaft 38.One set of floating suture ends 12 are wrapped around the crossbar 46and then routed through the handle 44 without capturing the ends withthe pinching pin 48. The other set of floating sutures are wrappedaround the crossbar 46, captured by the pinching pin 48, and then routedthrough the handle 44, as described previously. This allows one floatingsuture 12 to provide the tension required to deploy the anchor and pullsthe other floating suture 12 along with the anchor 10 as it deploys.This helps to ensure proper deployment and ensures that both floatingsutures 12 can slide easily within the anchor after it is deployed.

An additional feature is provided in the handle 44 to assist thepractitioner. In the event that the floating suture 12 ends becometangled and caught in the handle during payout, suture access slots 56(FIG. 23) are provided in the handle 44 to allow the practitioner to cutthe suture ends with a scalpel. This leaves enough length of floatingsuture 12 for the practitioner to complete the procedure. Reviewing FIG.23, which is a depiction of the handle portion 44 of the inserter 36,the handle top 44 a and handle bottom 44 b are illustrated for clarity.

Another consideration for the design of the inserter shaft 39 is theability to pass through a curved drill guide. In order to reach somelocations (i.e. low on the glenoid rim), and to provide an angle asclose to perpendicular to the surface as possible, a drill guide 58(FIG. 21) with an approximately 25 degree curve is used. The insertershaft 39 is flexible enough to pass through this curved guide.

The drill guide 58 is designed to work in conjunction with the inserter36 to deploy the anchor 10. The large surface area at the distal tip ofthe drill guide 58 lowers the pressure exerted on the bone surface 60during anchor deployment (FIG. 21). There are, in certain embodiments,two sizes of drill guides for the two anchor configurations, though, ofcourse, the inventive system contemplates the usage of more than twodifferent anchor configurations with a corresponding number of suitabledrill guides. The single-loaded anchor drill guide, in one illustrativeembodiment, has a tip surface area of 8.65 mm², compared toapproximately 4.25 mm² for a typical drill guide tip, an approximate 2:1ratio. This reduces the pressure on the bone by about one half for thesame applied force and greatly reduces the risk of the tip cutting intothe bone during anchor deployment or practitioner over-malleting. Italso provides an opposing force over a large surface area on the bonesurface, above the deploying anchor, to prevent the anchor from pullingout of the bone during tension.

Another alternative suture anchor embodiment 10 is illustrated in FIGS.24-27. This anchor is constructed by wrapping anchor suture around a pinand tying two alternative half-hitches 62 (FIG. 25). The two limbs arethen wrapped around another pin, and more half-hitches 62 are tied. Thecenter loop 64 is wrapped around a larger pin to allow for easierloading onto the inserter inner shaft 38. The floating suture or suturesare then passed through the loops 66 (created by the pins) to completethe construct.

This anchor is constructed by forming a double loop of suture, thenwrapping one of the free ends around the loop approximately twentytimes. The loop is then tightened around two posts a distance apart bypulling both free ends. This creates a loop, similar to the anchor loopof the previous double-loaded anchor embodiment 10 of FIGS. 10-18, Theremaining construction steps are the same as previously described—theanchor is wrapped around a snare with alternating twists and a floatingsuture is pulled through the openings to complete the construct.

In the foregoing described embodiments of the inserter 36, the crossbar46 travels a fixed distance before the sutures are released, resultingin a predetermined tension range to deploy the anchor 10. If desired,however, this distance—and therefore, the deployment tension—can beadjusted by the practitioner. For example, the practitioner may beconcerned about deploying in very soft or poor bone quality, and maywant to deploy the anchor with a lower tension. The lower pullout forcecan be compensated for by implanting more anchors or further restrictingthe patient's post-operative activity. An embodiment of this modifieddesign is illustrated in FIGS. 28 and 29. In this embodiment, adjustabledeployment tension requires an adjustable tension control knob or switch68 that the user can adjust as desired. In FIG. 28, the adjustabletension control 68 serves as a backstop and determines the position ofthe fixed pin 54. In this first position, the fixed pin 54 is in aproximal position a distance x from the control 68, which in oneillustrative embodiment is approximately 12 mm, and contacts thepinching pin 48 when the crossbar 46 reaches 20 mm of travel. Thepinching pin 48, and thus the deployment tension (T_(load)) is releasedwhen the crossbar travels 25 mm, in the illustrated example. This is thehigh deployment tension position (the same as in the fixed embodimentdescribed above).

However, when the adjustable tension control 68 is actuated to itssecond position, as shown in FIG. 29, a ramp 70 pushes the fixed pindistally, so that the fixed pin is in a distal position a distance yfrom the tension adjustment control 68. In the same illustrativeembodiment, this distance y is approximately 14 mm. In this position,the pinching pin 48 contacts the fixed pin when the crossbar 46 reaches18 mm of travel. The pinching pin, and thus, the deployment tension(T_(load)), is released when the crossbar 46 travels 23 mm. This reducedtravel results in a lower maximum tension (T_(load)) applied to thefloating sutures to deploy the anchor.

The tension adjustment control 68 may have two positions, asillustrated, comprising a “hard bone” position and a “soft bone”position, or it may alternatively be infinitely adjustable. The samefunction may be achieved with a slider or any other actuator whichchanges the position of the fixed pin with respect to the crossbar andthe pinching pin.

In the foregoing embodiments, the maximum tension applied by theinserter is limited by the fit of the fixed pin inside the crossbar. Thefloating sutures are pinched between these two components. When thetension becomes too high, the sutures will slip, placing a limit on theholding tension. T_(hold), and thus, on the deployment tension T_(load).If a more precise maximum deployment force were desired, the deploymenttension applied to the floating sutures could be limited by utilizing acompression spring between the cross pin and the crossbar. In such adesign, when the tension in the floating sutures exceeds the forceexerted by the spring at the given length, proximal movement of thecross pin would simply compress the spring and not continue to move thecrossbar proximally. Because the crossbar would not move, the onlyadditional tension applied to the floating sutures would be through thespring. By choosing the proper spring parameters (length, spring rate)and distances between the cross pin and crossbar, a maximum force may beapplied to the crossbar by the cross pin (through the spring), resultingin a maximum tension applied to the suture to deploy the anchor.

In the described inserter embodiments, the suture is wrapped around around crossbar in order to pull considerable tension on the floatingsutures. There are other methods, however, which may be used to securethe floating sutures, including spring clips, suture cleats, and thelike. A pinching pin is provided to secure the suture ends. This pin isreleased automatically when the inner shaft moves the designed distance.This pin may be replaced by a simple suture cleat on the crossbar andrely on the user to release the holding tension manually. This wouldrequire the suture ends to be accessible outside the handle.

Accordingly, although exemplary embodiments of the invention has beenshown and described, it is to be understood that all the terms usedherein are descriptive rather than limiting, and that many changes,modifications, and substitutions may be made by one having ordinaryskill in the art without departing from the spirit and scope of theinvention.

What is claimed is:
 1. A method of anchoring an anchor in a bone tunnel,comprising: delivering an anchor into a bone tunnel through an openingin an outer surface of a bone with at least a first tensioning suturecoupled to the anchor extending back through the bone tunnel and out ofthe opening in the outer surface of the bone, wherein said deliveringincludes advancing a leading end of a delivery shaft that is engagedwith the anchor through the opening in the outer surface of the bone toa first location in the bone tunnel; and withdrawing the delivery shaftfrom the bone tunnel after said delivering, wherein a first stage ofsaid withdrawing includes the leading end of the delivery shaft movingback through the bone tunnel from the first location in the bone tunnelto a second location in the bone tunnel without tension being applied tothe first tensioning suture, and wherein a second stage of saidwithdrawing includes the leading end of the delivery shaft moving backthrough the bone tunnel from the second location in the bone tunnel to athird location in the bone tunnel such that tension is applied to thefirst tensioning suture to pull the anchor a distance back through thebone tunnel and cause a lateral dimension of the anchor to expand in thebone tunnel for anchoring the anchor in the bone tunnel, and wherein athird stage of said withdrawing includes the leading end of the deliveryshaft moving back through the bone tunnel from the third location in thebone tunnel to a fourth location in the bone tunnel which releasestension from the first tensioning suture.
 2. The method of claim 1,wherein 60 N-150 N of tension is applied to the first tensioning sutureduring the second stage of said withdrawing.
 3. The method of claim 1,wherein the anchor is formed entirely out of suture material.
 4. Themethod of claim 3, wherein the anchor includes a plurality of loops withthe first tensioning suture extending through the plurality of loops. 5.The method of claim 4, wherein the anchor is in a folded configurationduring said delivering, and wherein the first stage of said withdrawingincludes the leading end of the delivery shaft being pulled out frombetween two folded sides of the anchor.
 6. The method of claim 1,wherein the delivery shaft does not rotate during said withdrawing. 7.The method of claim 1, wherein multiple tensioning sutures are coupledto the anchor.
 8. The method of claim 1, wherein said deliveringincludes the anchor and the delivery shaft passing through a drillguide.
 9. A method of anchoring an anchor in a bone tunnel, comprising:delivering an anchor into a bone tunnel through an opening in an outersurface of a bone with at least a first tensioning suture coupled to theanchor extending back through the bone tunnel and out of the opening inthe outer surface of the bone, wherein said delivering includesadvancing a leading end of a delivery shaft that is engaged with theanchor through the opening in the outer surface of the bone and toward adistal end of the bone tunnel; and moving, after said delivering, theleading end of the delivery shaft away from the distal end of the bonetunnel, wherein said moving includes: (a) the leading end of thedelivery shaft traveling over a first distance in the bone tunnel whichcauses no tension to be applied to the first tensioning suture; andsubsequently (b) the leading end of the delivery shaft traveling over asecond distance in the bone tunnel which causes tension to be applied tothe first tensioning suture which causes a lateral dimension of theanchor to expand in the bone tunnel for anchoring the anchor in the bonetunnel, wherein, after the leading end of the delivery shaft hastraveled over the second distance, said moving further includes theleading end of the delivery shaft traveling over a third distance in thebone tunnel which causes tension to be released from the firsttensioning suture.
 10. The method of claim 9, wherein 60 N-150 N oftension is applied to the first tensioning suture as the leading end ofthe delivery shaft travels over the second distance.
 11. The method ofclaim 9, wherein the anchor is formed entirely of soft material.
 12. Themethod of claim 9, wherein the anchor is formed entirely out of suturematerial.
 13. The method of claim 12, wherein the anchor includes aplurality of loops with the first tensioning suture extending throughthe plurality of loops.
 14. The method of claim 9, wherein the deliveryshaft does not rotate during said moving.
 15. The method of claim 9,wherein multiple tensioning sutures are coupled to the anchor.
 16. Themethod of claim 9, wherein said delivering includes the anchor and thedelivery shaft passing through a drill guide.
 17. The method of claim16, wherein the drill guide is curved.
 18. The method of claim 9,wherein the anchor is in a folded configuration during said delivering,and wherein the leading end of the delivery shaft traveling over thefirst distance includes the leading end being pulled out from betweentwo folded sides of the anchor.
 19. A method of anchoring an anchor in abone tunnel, comprising: delivering an anchor into a bone tunnel throughan opening in an outer surface of a bone with at least a firsttensioning suture coupled to the anchor extending back through the bonetunnel and out of the opening in the outer surface of the bone, whereinsaid delivering includes advancing a leading end of a delivery shaftthat is engaged with the anchor through the opening in the outer surfaceof the bone and toward a distal end of the bone tunnel; and withdrawingthe leading end of the delivery shaft back through the bone tunnel awayfrom the distal end of the bone tunnel, wherein said withdrawingincludes a suture tensioning phase followed by a tensioning releasephase which both occur while the leading end of the delivery shaftremains inside the bone tunnel, the suture tensioning phase occurringvia movement of the leading end of the delivery shaft back through thebone tunnel away from the distal end of the bone tunnel which causestension to be applied to the first tensioning suture and thereby causesa lateral dimension of the anchor to expand in the bone tunnel, thetensioning release phase occurring via further movement of the leadingend of the delivery shaft back through the bone tunnel away from thedistal end of the bone tunnel which causes tension to be released fromthe first tensioning suture.
 20. The method of claim 19, wherein theanchor is formed entirely out of suture material.
 21. The method ofclaim 20, wherein the anchor includes a plurality of loops with thefirst tensioning suture extending through the plurality of loops. 22.The method of claim 21, wherein 60 N-150 N of tension is applied to thefirst tensioning suture during the suture tensioning phase.